Clair River Research Articles

“This is the mess that we are living in”: residents everyday life experiences of living in a stigmatized community

This paper is part of a larger community health study aimed at delineating the determinants of health in Sarnia. The paper specifically investigates Sarnia residents’ daily lived experiences, perceptions of and responses to living within the St. Clair River “Area of Concern” (AOC) as designated by the federal government based on the hypothesis that relatively high levels of environmental pollution in the region are negatively influencing human health. Results from in-depth interviews (N = 27) show that residents of Sarnia are conflicted by the elevation of awareness about environmental health threats by being labelled within an AOC. Residents use their emotional and sensual experiences to adopt appropriate coping strategies to live within a contaminated community. In contextualizing their everyday lived realities, residents argued that living in an AOC demands personal acceptance of the conditions in Sarnia and awareness of “bad air days” to cope with pollution exposure. Yet, residents were not willing to abandon Sarnia because of their cultural, social, and economical attachments to the place they call home. These findings suggest the need for local health policies that incorporate local concerns and perceptions of how environmental pollution affects people’s experiences and well-being. There is a necessity to involve community members as central participants in the process of policy making.

Contaminant Trends in Suspended Sediments in the Detroit River-Lake St. Clair-St. Clair River Corridor, 2000 to 2004

Abstract Suspended sediments from the Detroit River-Lake St. Clair-St. Clair River corridor over the period of 2000 to 2004 were analyzed to examine the spatial distributions of contaminants including polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and mercury. Contaminant spatial distributions were similar over the five-year study period, but concentrations varied considerably among sampling locations. Concentrations of PCBs ranged from 22 to 1,200 ng/g (dry weight) in 2004, and from 10 to 2,700 ng/g (dry weight) in 2000; concentrations of PAHs ranged from 640 to 52,000 ng/g (dry weight) in 2004, and from 240 to 82,000 ng/g (dry weight) in 2000; and concentrations of mercury ranged from 0.063 to 0.478 mg/kg (dry weight) in 2004, and from 0.060 to 0.514 mg/kg (dry weight) in 2002. The highest PCB and PAH concentrations were associated with suspended sediments in the lower and middle reaches of the Detroit River in the area of the Trenton Channel, and the outflow of the Rouge River. The spatial distributions of mercury were more consistent throughout the entire corridor, indicating the presence of sources in both the lower reaches of the Detroit River and the upper reaches of the St. Clair River. Both the Trenton Channel area of the Detroit River and the upper reaches of the St. Clair River are characterized by heavy historical industrial activity, including steel manufacturing and chlor-alkali production.

Temporal and spatial trends of organochlorines and mercury in fishes from the St. Clair River/Lake St. Clair corridor, Canada

The temporal and spatial relationships of a suite of organochlorine contaminants and mercury were examined in various fish species of the St. Clair River/Lake St. Clair corridor, Canada, in order to evaluate the effectiveness of remediation efforts and to assess the risk to human and wildlife fish consumers. In Lake St. Clair, fish tissue concentrations of mercury, polychlorinated biphenyls (PCBs), octachlorostyrene (OCS), hexachlorobenzene (HCB), and dichlorodiphenyltrichloroethane (DDT) decreased consistently from the 1970s until the 1980s and 1990s, after which the rate of contaminant decline slowed or concentrations stabilized. This trend was consistent in up to 13 species (both young-of-the-year and adult fishes) comprising different trophic positions and dietary habits, suggesting that the changes were reflective of ambient conditions rather than food web processes. Elevated concentrations of mercury, PCBs, OCS, HCB, and DDT were detected in St. Clair River young-of-the-year spottail shiner compared with fish from Lake Huron, indicating that non-atmospheric inputs of these chemicals, likely originating from sediment, remain in the St. Clair River. Current concentrations of mercury and PCBs, and mercury, PCBs, and DDT remain of concern to human and wildlife fish consumers, respectively. Given that contaminant decreases have generally stabilized in fish, we suggest that further natural recovery of contaminants in St. Clair corridor fishes will be slow since contaminants will likely continue to be influenced by sediment levels.

Real-Time Hydraulic and Hydrodynamic Model of the St. Clair River, Lake St. Clair, Detroit River System

The Huron-Erie Corridor serves as a major waterway in the Great Lakes and is the connecting channel between Lake Huron and Lake Erie. The system consists of the St. Clair River, Lake St. Clair, and the Detroit River, and serves as a recreational waterway, source of drinking water for Detroit and surrounding cities, as well as the only shipping channel to Lakes Huron, Michigan, and Superior. This paper describes a three-dimensional unsteady model of the combined system and its application to real-time predictions of physical conditions over the corridor. The hydrodynamic model produces nowcasts eight times per day and 48 h forecasts twice a day. Comparisons between model simulations and observed values show average differences of 3 cm for water levels and 12 cm/s for along-channel currents in the St. Clair River (compared to mean current values of 1.7 m/s) for the period of September 2007 to August 2008. Simulations reveal a spatially and temporally variable circulation in Lake St. Clair as well as significant changes in flow rate and distribution through the St. Clair Delta not accounted for in previous models.

First record ofPolypodium hydriforme(Cnidaria) from lake sturgeon (Acipenser fulvescens Rafinesque) in the St. Clair River, Michigan

Journal of Applied IchthyologyVolume 25, Issue s2 p. 107-108 First record of Polypodium hydriforme (Cnidaria) from lake sturgeon (Acipenser fulvescens Rafinesque) in the St. Clair River, Michigan M. V. Thomas, M. V. Thomas Michigan Department of Natural Resources, Lake St Clair Fisheries Research Station, Mt. Clemens, Michigan, USASearch for more papers by this authorP. M. Muzzall, P. M. Muzzall Department of Zoology, Natural Science Building, Michigan State University, East Lansing, Michigan, USASearch for more papers by this author M. V. Thomas, M. V. Thomas Michigan Department of Natural Resources, Lake St Clair Fisheries Research Station, Mt. Clemens, Michigan, USASearch for more papers by this authorP. M. Muzzall, P. M. Muzzall Department of Zoology, Natural Science Building, Michigan State University, East Lansing, Michigan, USASearch for more papers by this author First published: 01 September 2009 https://doi.org/10.1111/j.1439-0426.2009.01277.xCitations: 1 Author’s address: Michael V. Thomas, Michigan Department of Natural Resources, Lake St. Clair Fisheries Research Station, 33135 S. River Road, Mt. Clemens, MI 48045, USA.E-mail: [email protected] Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume25, Issues2Special Issue: Proceedings of the Inaugural Meeting of the North American Chapter of the World Sturgeon Conservation Society, Ottawa, Canada, August 19‐21, 2008October 2009Pages 107-108 RelatedInformation

Sex assignment of lake sturgeon (Acipenser fluvescens) based on plasma sex hormone and vitellogenin levels

Summary This study focused on identifying the sex of lake sturgeon by measuring the sex hormones estradiol and testosterone, and the phosphoprotein vitellogenin (Vtg) in blood plasma by radioimmunoassay and enzyme-linked immunosorbent assay, respectively, and evaluating these techniques as tools in lake sturgeon population management. Surveys of the St Clair River (SCR) lake sturgeon population have characterized it as rebounding by having steady or increasing recruitment since 1997. However, researchers have not been able to effectively determine the sex for most of the sturgeon they capture because few fish caught during surveys are releasing gametes. A total of 115 fish were sampled from May through June in 2004 and 2005 from the SCR, Michigan, USA. Of these, only four females and eight males were verified (i.e. they were releasing gametes at time of capture), resulting in very few fish with which to validate blood hormone and Vtg biomarkers of sex. Fifty-six percent of the fish were assigned a sex designation based on biomarker criteria. Correspondence between actual gonadal sex and biomarker-directed classification was good for the small subset of fish for which gonadal sex was definitively determined. Moreover, application of the steroid values in a predictive sex assignment model developed for white sturgeon misclassified only the same two fish that were misclassified with the steroid and Vtg biomarkers. The experimental results suggest a sex ratio of 1 : 2.7 (F:M), however more conclusive methods are needed to confirm this ratio because so few fish were available for sex validation. Of the 43 males, 14 were within the legal slot limit, 11 were smaller than 1067 mm total length (TL), and 18 were larger than 1270 mm TL. All 15 females were larger than 1270 mm TL, and thus protected by the slot limit criteria. Considering that lake sturgeon are threatened in Michigan, an advantage to using blood plasma assays was that fish were not harmed, and sample collection was quick, simple, and inexpensive. However, because a sufficiently large number of fish could not be validated for gonadal sex due to handling restrictions given the fish’s protected status, assignment of sex is not based on a robust multi-variate model. An immediate alternative may be to use other non-invasive field methods (e.g. ultrasound, fiber-optic endoscope) to provide a more timely classification while establishing well-validated plasma hormone and Vtg-based predictive models for sex assignment of lake sturgeon.

Secondary invasion of the round goby into high diversity Great Lakes tributaries and species at risk hotspots: potential new concerns for endangered freshwater species

The round goby (Neogobius melanostomus) first invaded North America in 1990 when it was discovered in the St. Clair River. Despite more than 15 years of potential invasion, many Great Lakes’ lotic systems remained uninvaded. Recently, we captured the round goby from several Great Lakes tributaries known as species-at-risk hotspots. With a combination of field sampling of round gobies and literature review of the impact of round gobies on native taxa, we assess the potential impacts of the secondary invasion to native species using three mechanisms: competition; predation; and indirect impacts from the loss of obligate mussel hosts. We estimate that 89% (17/19) of benthic fishes and 17% (6/36) of mussels that occur in these systems are either known or suspected to be impacted by the secondary invasion of round goby. In particular, we note that the distribution of potential impacts of round goby invasion was largely associated with species with a conservation designation, including seven endangered species (1 fish, 6 mussels). As these recent captures of round goby represent novel occurrences in high diversity watersheds, understanding the potential impacts of secondary invasion to native biota is fundamental to prevent species declines and to allow early mitigation.

Characteristics of a refuge for native freshwater mussels (Bivalvia: Unionidae) in Lake St. Clair

The Lake St. Clair delta (∼ 100 km 2) provides an important refuge for native freshwater mussels (Unionidae) wherein 22 of the ∼ 35 historical species co-occur with invasive dreissenids. A total of 1875 live unionids representing 22 species were found during snorkeling surveys of 32 shallow (∼ 1 m) sites throughout the delta. Richness and density of unionids and zebra mussel infestation rates varied among sites from 3 to 13 unionid species, 0.02 to 0.12 unionids/m 2, and < 1 to 35 zebra mussels/unionid, respectively. Zebra mussel infestation of unionids in the delta appears to be mitigated by dominant offshore currents, which limit densities of zebra mussel veligers in nearshore compared to offshore waters (13,600 vs. 28,000/m 3, respectively). Glycogen concentrations in the tissues of a common and widespread species in the delta ( Lampsilis siliquoidea) suggest that zebra mussels may be adversely affecting physiological condition of unionids in a portion of the Lake St. Clair delta. Physiological condition and community structure of unionids within the delta may also be influenced by differences in food quantity and quality resulting from the uneven distribution of water flowing from the St. Clair River. The delta likely supports the largest living unionid community in the lower Great Lakes and includes several species that have been listed as Endangered or Threatened in Canada and/or the state of Michigan, making it an important refuge for the conservation of native unionids.

The International Joint Commission's Role in the United States-Canada Transboundary Air Pollution Control Regime: A Century of Experience to Guide the Future

The International Joint Commission (IJC), a bilateral institution established to manage the shared water resources of the United States and Canada, is celebrating its centennial. Despite its original mandate, the IJC also earned a prominent role in the governance of transboundary air pollution between the two nations. This article reviews the evolution of that particular function, evaluating the IJC’s role in the international transboundary air pollution regime with an eye to the challenges apparent at the dawn of its second century. The birth of the IJC and its original mandate under the 1909 Boundary Waters Treaty are introduced first. Next, every reference made to the IJC directly confronting air pollution are presented and analyzed. A pattern of increasing responsibility is traced from Trail Smelter through the series of three Detroit-St. Clair River Region references, then beyond the Great Lakes Water Quality Agreements to the 1991 U.S.-Canada Air Quality Agreement. After evaluating those experiences, four proposals are distilled which would help to restore the IJC to the forefront of the U.S.-Canada transboundary air pollution control regime. Namely, the "precautionary principle" of international environmental law should be directly applied when drafting future references for submission to the IJC; the evidentiary value of IJC reports should be recognized in domestic courts on both sides of the border (especially in the context of the transboundary litigation provisions recorded in section 115 of the U.S. Clean Air Act and section 21.1 of the Canadian Clean Air Act); the Boundary Waters Treaty should be revised to transform IJC arbitration into an attractive alternative to litigation; and the IJC should be granted all of its familiar roles vis-a-vis the upcoming transboundary air pollution cap and trade program.

The invasive round goby Apollonia melanostoma (Actinopterygii: Gobiidae) - a new intermediate host of the trematode Neochasmus umbellus (Trematoda: Cryptogonimidae) in Lake Erie, Ohio, USA

The invasive round goby Apollonia melanostoma (Actinopterygii: Gobiidae) - a new intermediate host of the trematode Neochasmus umbellus (Trematoda: Cryptogonimidae) in Lake Erie, Ohio, USA

Contemporary Subsidence and Ground Movement, Southwestern Ontario: Possible Bedrock Controls

Ground movement, principally subsidence with limited strike-slip displacement, occurs discontinuously along an 8 km-long, north-south zone which is subparallel to the St. Clair River and extends from Mooretown to Corunna, Ontario. The southern-most area of subsidence lies beneath the river, 25 m from the Canadian shore. The longest continuous interval of subsidence is ^ 75 m east of the river and the northern limit is located about 250 to 300 m east of the river. Subsidence has been both abrupt and gradual, occurring overnight and over a two-year period. In the south and central areas the west side (the side closer to the river) has dropped 20 to 40 cm. However, in the north, the east side has subsided. The foundation of one home has been displaced 1 and 5 cm, in a right-lateral sense, along two discrete surfaces. The ground movements do not resemble surface slumping. Bedrock movement resulting from either dissolution of limestone or salt, displacements along Grenville basement structures, or a combination of the two may explain the phenomenon. The deformation observed, both in the production of scarps and damage to civil structures, may have neotectonic implications.

Genetic diversity and population structure ofEscherichia coliisolated from freshwater beaches

Escherichia coli is an important member of the gastrointestinal tract of humans and warm-blooded animals (primary habitat). In the external environment outside the host (secondary habitat), it is often considered to be only a transient member of the microbiota found in water and soil, although recent evidence suggests that some strains can persist in temperate soils and freshwater beaches. Here we quantified the population genetic structure of E. coli from a longitudinal collection of environmental strains isolated from six freshwater beaches along Lake Huron and the St. Clair River in Michigan. Multilocus enzyme electrophoresis (MLEE) and multilocus sequence typing (MLST) revealed extensive genetic diversity among 185 E. coli isolates with an average of 40 alleles per locus. Despite evidence for extensive recombination generating new alleles and genotypic diversity, several genotypes marked by distinct MLEE and MLST profiles were repeatedly recovered from separate sites at different times. A PCR-based phylogrouping technique showed that the persistent, naturalized E. coli belonged to the B1 group. These results support the hypothesis that persistent genotypes have an adaptive advantage in the secondary habitat outside the host.

Probing for Passage: The St. Clair Tunnel

This article provides an historical account of the construction of the St. Clair tunnel that connected the U.S. with its northern neighbor Canada under the St. Clair River in eastern Michigan in 1890. This first subaqueous tunnel to be built in North America was necessitated by the political difficulties of bridge-building at the time, as bridges were to allow for boats with even the tallest masts to travel safely below. As Grand Trunk Railway wished to cross the river, the company contracted the Canadian engineer Joseph Hobson for the 8,000 foot long tunnel. Hobson, who found there to be both shale and blue clay underneath the river, decided to tunnel through the clay, which he thought to be the more stable of the two. The tunnel was excavated from both sides using a steel shell that was pushed along as progress was made. Hobson also made use of air pressurization in the tunnel at a time when such technology was little-used.

Spatial Distributions and Temporal Trends in Sediment Contamination in Lake St. Clair

The sediments of Lake St. Clair were surveyed in 2001 for a range of compound classes including metals (such as total mercury and lead), polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and dibenzofurans, organochlorine pesticides, polycyclic aromatic hydrocarbons, and short- and medium- chain chlorinated paraffins, in order to evaluate the spatial distribution and temporal trends of contamination. Concentrations of contaminants were generally low compared to the lower Great Lakes (Erie and Ontario), and were typically below the Canadian Sediment Quality Probable Effect Level (PEL) guidelines. The only exceptions were for mercury and DDE, where concentrations exceeded their respective PEL at one of the thirty-four sites sampled. With the exception of mercury, it was difficult to interpret spatial trends in contaminant concentrations due to these low levels, although relatively elevated concentrations of several contaminants were found in L’Anse Creuse Bay and at the outflow of the Thames River. In the case of mercury, historically-contaminated sediments in the St. Clair River associated with chlor-alkali production appeared to contribute to loadings to Lake St. Clair. There have been substantial reductions in sediment contamination in Lake St. Clair over the past three decades, as determined through sediment core profiles as well as through comparison of current data to those from historical surveys conducted in the early 1970s. These results indicate that management actions to reduce contaminant loadings to Lake St. Clair have been generally successful.

Occurrence of Virulence and Antimicrobial Resistance Genes in Escherichia coli Isolates from Different Aquatic Ecosystems within the St. Clair River and Detroit River Areas

Although the number of Escherichia coli bacteria in surface waters can differ greatly between locations, relatively little is known about the distribution of E. coli pathotypes in surface waters used as sources for drinking or recreation. DNA microarray technology is a suitable tool for this type of study due to its ability to detect high numbers of virulence and antimicrobial resistance genes simultaneously. Pathotype, phylogenetic group, and antimicrobial resistance gene profiles were determined for 308 E. coli isolates from surface water samples collected from diverse aquatic ecosystems at six different sites in the St. Clair River and Detroit River areas. A higher frequency (48%) of E. coli isolates possessing virulence and antimicrobial resistance genes was observed in an urban site located downstream of wastewater effluent outfalls than in the other examined sites (average of 24%). Most E. coli pathotypes were extraintestinal pathogenic E. coli (ExPEC) pathotypes and belonged to phylogenetic groups B2 and D. The ExPEC pathotypes were found to occur across all aquatic ecosystems investigated, including riverine, estuarine, and offshore lake locations. The results of this environmental study using DNA microarrays highlight the widespread distribution of E. coli pathotypes in aquatic ecosystems and the potential public health threat of E. coli pathotypes originating from municipal wastewater sources.

A multiproxy environmental investigation of Holocene wood from a submerged conifer forest in Lake Huron, USA

Remains of a Holocene drowned forest in southern Lake Huron discovered in 12.5 m of water (164 m above sea level), 4.5 km east of Lexington, Michigan USA (Sanilac site), provided wood to investigate environment and lake history using several proxies. Macrofossil evidence indicates a forest comprised primarily of conifers equivalent to the modern “rich conifer swamp” community, despite generally low regional abundance of these species in pollen records. Ages range from 7095 ± 50 to 6420 ± 70 14C yr BP, but the clustering of stump dates and the development of 2 floating tree-ring chronologies suggest a briefer forest interval of no more than c. 400 years. Dendrochronological analysis indicates an environment with high inter-annual climate variability. Stable-carbon isotope composition falls within the range of modern trees from this region, but the stable-oxygen composition is consistent with warmer conditions than today. Both our tree-ring and isotope data provide support for a warmer environment in this region, consistent with a mid-Holocene thermal maximum. This drowned forest also provides a dated elevation in the Nipissing transgression at about 6420 14C yr BP (7350 cal yr BP) in the southern Lake Huron basin, a few hundred years before reopening of the St. Clair River drainage.

A Reconstruction of Lake Michigan–Huron Water Levels Derived fromTree Ring Chronologies for the Period 1600–1961

A dendrochronolgy of annual precipitation and air temperatures from six Great Lakes locations was used to reconstruct Lake Michigan-Huron water levels from 1600–1961 representing the present St. Clair River channel conditions and basin land cover. The reconstructions are based upon a multi-linear regression model relating multi-year annual precipitation and air temperature to annual water levels. An increased frequency of low lake levels was found to occur prior to the twentieth century, accompanied by a major extreme in water levels, greater than that experienced in the historical record, in the early 1600s. The comparison of simulated and measured water levels also indicates that the impact of some of the channel changes in the St. Clair River may be underestimated and that the major drop in lake level in the 1880s may be due to erosion as well as to decreased precipitation. The occurrence of extreme levels around 1640, in 1838, and in 1986 suggests a return interval of 150–190 years for extreme lake levels. The analysis also suggests that the variability of lake levels has greatly decreased over the last century when comparing tree-ring-derived level variability. Thus climatic periods used for the development of the current regulation plans may not be representative of the longer-term climate and lake levels.

Temporal and Spatial Trends in Chlorinated Hydrocarbon Concentrations of Mink in Canadian Lakes Erie and St. Clair

Mink (Mustela vison) carcasses were collected from local commercial trappers from fall 1998 to spring 2003 from tributaries and marshes within 4.8 km from the shores of Lakes Erie and St. Clair, including the Wheatley Harbour and St. Clair River Areas of Concern (AOCs), as well as from inland sites (8 to 40 km from shore). Liver concentrations, on a lipid weight basis, of chlorinated hydrocarbons were measured and compared among sites and to tissue concentrations of mink from two previous collections from similar sites over the past 25 years. Mink from the western Lake Erie sites, which included the Wheatley Harbour AOC, had significantly higher concentrations of sum PCBs and PCB Aroclors than those from the St. Clair corridor or inland sites, with concentrations from the rest of Lake Erie being intermediate. Dieldrin concentrations were also significantly higher in western Lake Erie than many other sites, and those of oxychlordane and mirex also tended to be higher (0.05 < p < 0.1). There were no differences in contaminant concentrations between the St. Clair River AOC and the downstream non-AOC Lake St. Clair site, with the exception of slightly higher levels of octachlorostyrene (OCS). Concentrations of PCBs and other chlorinated hydrocarbons in mink showed a general decrease over the past two decades. In contrast, PCBs and some organochlorine pesticides tended to increase, significantly so with oxychlordane, in western Lake Erie mink over the same time period. DDE declined at all sites. Currently, mink liver PCB concentrations are within the range associated with reproductive impairment, as determined from captive mink studies, in 11.7% of all animals collected from the Lakes Erie and St. Clair basin overall, but in almost 40% of individuals from western Lake Erie.

Formation of the St. Clair River Delta in the Laurentian Great Lakes System

The St. Clair River delta, the largest in the Laurentian Great Lakes system, is located in Lake St. Clair at the mouth of the St. Clair River. It straddles the border between the state of Michigan in the USA and the province of Ontario in Canada. The current study aims at characterizing and explaining the formation and evolution of the distributary channels in the St. Clair River delta and the delta itself. The delta is classified as a river dominated feature with classic “bird's foot” structure similar to the Mississippi delta model. The delta is composed of two surfaces. The older surface at the delta apex was deposited at a higher lake level some 3,500 to 5,000 years B.P. The current delta started to form following a drop in lake level some 3,500 years B.P. and continues to build to the present day. The delta consists of seven active deep channels averaging 11 m in depth entering a lake with a mean depth of 3 m with much shallower water in the delta front region. The channels are stable and are actively eroding into the sediments of the lake creating both sub-aqueous and sub-aerial levee deposits with crevasses. The interdistributary bays are being filled with sandy deposits created by wave energy and by crevasse deposits. At the erosional front of each distributary a narrow erosional notch “leading channel” is being formed which appears to control the direction of lakeward erosion of each deep distributary channel. The emplacement of the delta body in the shallow receiving water body has been termed “burrowing” delta formation and is the mechanism controlling the formation of this sedimentary feature.

Shift in Sex Ratio: Male Numbers Sink in Great Lakes Community

Vol. 113, No. 10 EnvironewsOpen AccessShift in Sex Ratio: Male Numbers Sink in Great Lakes Communityis accompanied byDeclining Sex Ratio in a First Nation Community Ernie Hood Ernie Hood Search for more papers by this author Published:1 October 2005https://doi.org/10.1289/ehp.113-a686bCited by:1AboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit Sex ratio—the proportion of male to female live births—can be an important indicator of the reproductive health of a population, whether animal or human. This figure is typically fairly constant. For example, the worldwide human sex ratio ranges from 102 to 108 male births for every 100 female births; in other words, male babies make up about 50.4–51.9% of live births worldwide. Now, however, investigators have documented a significant skewing of the human sex ratio in a population located in a heavily polluted Great Lakes area [EHP 113:1295–1298].In response to concerns about a shifting sex ratio among members of the Aamjiwnaang First Nation community near Sarnia, Ontario, a team of Canadian researchers examined birth records for the group from the years 1984–2003 as part of a broader community-based investigation. The researchers discovered that, as community members had suspected, there had been a significant and precipitous shift in the sex ratio.The expected sex ratio in Canada is 51.2% male babies to 48.8% female babies. For the period 1984–1992, that ratio held fairly constant among this community. In the period 1993–2003, however, male babies made up only 41.2% of live births. The five-year period from 1999 to 2003 showed an even sharper decline, with male babies making up 34.8% of live births. According to the researchers, although there is normal variation in sex ratio within populations, the deviation in this case appears to be outside the normal range.Although there is as yet no direct evidence linking this human sex ratio decline to environmental exposures, the circumstantial evidence suggests there may be a connection. The Chippewas of the Aamjiwnaang reserve reside within the St. Clair River Area of Concern, situated immediately adjacent to several large petrochemical, polymer, and chemical industrial plants. The area is one of Canada’s largest concentrations of industry. Prior soil and sediment assessment has shown that the reserve land is heavily contaminated with pollutants such as polychlorinated biphenyls, polyaromatic hydrocarbons, hexachlorobenzene, mirex, a variety of potentially toxic metals, volatile organic compounds, phthalates, and dioxins; many of these are known or suspected endocrine disruptors.As the investigators point out, past studies have documented reproductive outcomes in wildlife populations within the same region, including reduced hatching success, altered sexual development, and changes in sex ratios. Scientific suspicion has long been focused on environmental endocrine disruptor exposures as the root cause of these effects.The authors acknowledge that there are many other potential factors that could influence the declining sex ratio they describe. But the combination of close proximity to industrial facilities emitting known endocrine-disrupting chemicals and the documented adverse reproductive outcomes in wildlife populations in the region leads them to conclude that further investigations are warranted into the types and routes of chemical exposures—via air, water, food, soil, and sediment—for this population. A community health survey designed to explore health concerns among residents of the reserve is in progress, including information on potential covariates that may influence the sex ratio, such as parental age or smoking.Chemical culprit?The Sarnia–Lambton area in Ontario is home to Chemical Valley as well as the Aamjiwnaang First Nation community, which has experienced a significant skewing of the ratio of male to female babies born in recent years, leading some to question whether environmental exposures may be to blame.FiguresReferencesRelatedDetailsCited by Jackson L and Ellis W (2022) Prejudice in the Lives of Children and Adolescents Reference Module in Biomedical Sciences, 10.1016/B978-0-12-818872-9.00077-7, . Related articlesDeclining Sex Ratio in a First Nation Community17 August 2005Environmental Health Perspectives Vol. 113, No. 10 October 2005Metrics About Article Metrics Publication History Originally published1 October 2005Published in print1 October 2005 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]. Our staff will work with you to assess and meet your accessibility needs within 3 working days.